Fourier transform infrared spectroscopy study on effects of temperature on hydrogen bonding in amine-containing polyurethanes and poly(urethane-urea)s

Three types of amine-containing polyurethanes and poly(urethane-ureas), N-methyldi-ethanolamine (MDEA) and/or tetraethylenepentamine (TEPA) as the chain extender and poly(ethylene glycol) of MW 400 as the soft-segment component, have been studied by FTIR. The hydrogen bonding in hard and soft segments was examined for the extent of phase separation, and the microstructure was evidenced by differential scanning calonmetry (DSC). The temperature effects on the hydrogen bonding were also investigated. They show a significant amount of hydrogen bonding between the hard and soft segments. It indicates that there exists a large amount of partial phase mixing of hard and soft segments compared to the conventional polyurethanes. The bulky CH₃ groups of MDEA in hard segments restrict the hydrogen bonding within the hard segments, while the TEPA-containing urethane-urea polymers have more distinct phase separation. However, all of the polymers studied are amorphous materials such that the dissolved soft segments in the hard-segment domains may interfere with molecular packing in the domains. It shows that the hydrogen bonding in theae polymers persists up to 200°C. The hydrogen bonding of NH to the ether oxygen decreases significantly at T > 50°C.